Correlation of solubility data of azo disperse dyes with the dye uptake ofpoly(ethylene terephthalate) fibres in supercritical carbon dioxide

Solubility data of azo disperse dyes in supercritical carbon dioxide are pr esented for dyeings of poly(ethylene terephthalate) fibres with CI Disperse Red 167:1, carried out at 200-300 bar and 80-120 degreesC, with varying am ounts of adulterants The same dyeings were also carried out in water for co mparison. Scanning electron micrographs were taken of the dyes which show a growth of dye crystals during treatment in supercritical carbon dioxide. T he paper reports that at 120 degreesC, melting of the pure dye CI Disperse Red 167:1 is observed. The presence of adulterants in the dye formulations help prevent agglomeration by acting as spacers between the dye molecules. Dyeings of poly(ethylene terephthalate) carried out under conditions of the highest solubility of the dye in supercritical carbon dioxide do not neces sarily result in a very high dye uptake. This was shown by pressure- and te mperature-dependent dyeing experiments of poly(ethylene terephthalate) in s upercritical carbon dioxide.